GMAW and MIG torches are widely used to weld metallic materials. Referring to FIG. 1A, a GMAW or MIG torch 1 generally includes a torch body 2, a wire electrode that is fed through the torch body by a wire feeder 3, a nozzle 4, a gas diffuser, electrical connections and a power supply. A contact tip provides a point of electrical contact enabling the welding current to pass into the electrode wire as it feeds through the contact tip. When the welding current passes through the electrode wire, the wire melts and can be used to weld pieces of metal together.
The electrode wire is fed in through the back (or distal) end of the torch body and is melted at the contact tip on the front (or proximal) end of the torch. Within the torch body, a liner, which is a tube (or conduit), surrounds and prevents the electrode wire from kinking. Typically, the liner is fastened at the distal end of the torch body by a retainer (e.g., a screw or clamp) and extends proximally to the front of the torch body adjacent to the contact tip.
Liners are a consumable part of welding torches that periodically need to be replaced. Generally, liners are a single piece unit that are installed and removed through the distal end of the torch. In both robotic and manual applications, the removal and installation of a liner requires a weld operator to remove the nozzle, the contact tip, and the gas diffuser from a proximal end 40 of the welding torch. Next, the weld operator removes the torch from the wire feeder, which requires the weld operator to access a distal end 46 of the torch. This step necessitates that the weld operator move around the welding apparatus (e.g., torch and robotic arm), which requires care as it can lead to operator injury. Prior to removing the liner from the torch's distal end 46, the weld operator cuts the electrode wire and then pulls the liner 5 distally through the torch 1 (see FIG. 1B). The weld operator then inserts a new liner in a proximal direction into the distal end 46 of the torch. The weld operator advances the liner 5 until the inserted end of the liner extends pass (e.g., a few centimeters pass, a few inches pass) the proximal end 40 of the torch body. The torch is then reconnected to the wire feeder, the liner is cut to size, and the electrode wire is fed through the torch. Feeding the electrode wire from the distal end of the torch to the proximal end of the torch is usually accomplished via robotic control or through a manual feed button on the wire feeder. This process can be time consuming depending on the wire feed speed settings on the wire feeder. Finally, the gas diffuser, contact tip, and nozzle are reattached to the proximal end 40 of the torch.